Trailer wiring harness 2000 venture

When l purchased my van it came with a wire harness for towing. My van came with the tow package. where does this harness hook up to.

here is a link for you to look at:http://www.automotiveforums.com/vbulletin/showthread.php?t=581090

on my 2002 olds van the factory wire is up behind the drivers rear tire by the air comp. it has a dummy plug in the conection. i removed it and ran it to the rear hitch. to run the flat four wire plug you will need the wire converter to have the lights work right.i think it's a rpo code V92 for the trailor provision